Ferris regularly hunts for hair ties (I use the wide black ones with no metal band in it.)
He also loves to play with plastic spoons.
Max prefers plastic knives and forks.
Another "toy" Max seems to enjoy is the strip that is removed from the top of a zip-close bag, for instance, from the top of the pouch of cat treats. He'll go bonkers chasing that around the house.
Max also likes to play with the caps from my roomie's shaving cream cans and toilet paper rolls (of course!) And he takes pens out of the mug I keep them in on my desk - I find them on the floor all the time.
Penny gets a thrill out of the packing peanuts made from cornstarch (which are the only kind I let her play with.)
Ginger, however, seems to prefer her very own tail to any kind of manmade item.